Vehicular-type asphalt roadbed heater



Dec. 8, 1964 c. w. SOWELL VEHICULAR-TYPE ASPHALT ROADBED HEATER 5Sheets-Sheet 1 Original Filed Feb. 9, 1962 INVENTOR.

CZAFE/VCE 14 Jan/14 wk n ig/4 m AGENT 7 /Ill Dec. 8, 1964 c. w. SOWELL3,160,154

VEHICULAR-TYPE ASPHALT ROADBED HEATER Original Filed Feb. 9, 1962 3Sheets-Sheet 2 FIG. 5

FIG.6

INVENTOR. azn z/vce m Jon 14 2mm. MW

Dec. 8, 1964 c. w. SOWELL 3,160,154

VEHICULAR-TYPE ASPHALT ROADBED HEATER Original Filed Feb. 9, 1962 sSheets-Sheet s 9 77 7a m; I 7'5 75 75 FIG. 9

INVENTOR CZ4FN6E m Jon 14 AGENT United States Patent 7 3,160,154VEIHCULAR-TYPE ASPHA T RQADBEB HEATER (Ilarence W. Sowell, 16248 Itasca,Sepulyeda, Calif. Continuation of application Ser. No. 172,213, Feb. 9,1962. This application Aug. 6, 1964, Ser. No. 338,019

12 Claims. (Cl. 126-2712.)

This application is a continuation of application Serial No. 172,213,filed February 9, 1962.

The invention herein set forth pertains to surface heaters, and moreparticularly to a vehicular type asphalt roadbed heater.

The instant invention is an improvement upon the equipment described inmy Patent No. 2,558,160, which issued June 26, 1951, to which referencewill frequently be made in this specification; in fact, apparatustherein illustrated and described will not be illustrated and discussedin the present application, excepting in cases where some of thecomponents of the earlier structure are elements of the new combinationsembodying the present invention as set forth in the appended claims.

The patent to which reference has just been made disclosed a heatercarried by a chassis frame of substantially the maximum width permittedon most city streets, but provisions were therein set forth for movingthe heater laterally with respect to the chassis in order to permitgreater lateral coverage of the roadbed than the width of the heaterwould otherwise allow. The increased broadside range of heating made itpossible to use the heater closer to curbs and streetcar tracks thanwould otherwise be the case, and to obtain this additional coveragewithout any lateral movement of the chassis.

One of the primary objects of the present invention is to extend thelateral coverage in a practical manner beyond the limits permissiblewith the structure set forth in my earlier patent. This is accomplishedby providing the firebox with removable side plates and with pivotallymounted side extensions that may be rotated downwardly at will from aparked position over the hood to a working position in which they for-mcontinuations of the firebox that greatly expand its width.

Another object is to provide a firebox with hinged side extensions thatmay be selectively used to provide such different firebox widths thatcombinations thereof will correspond to the width of the street. This isimportant because there should be no overlapping of successive passesover the asphalt. If the main hood or firebox is 8 feet wide, fourpasses without using either of the side extensions will cover a street32 feet in width, but if the side extensions are 2 feet across, the samestreet may be covered by two traversais using one side extension to givefoot spreads and one traversal with both side extensions down to coverthe remaining .12 feet. Or two passes with a total firebox width of 12feet and one of 10 feet would I also do the job. A street 30 feet widecould be covered in three sweeps using a firebox 8 feet across and oneside 1 extension 2 feet wide. And it will readily be seen that streetsof various widths up to 48 feet can be covered in no more than fourpasses. Since most cities will not permit equipment more than 8feet-wide to move from one job site to another, it would take sixtraversals of a firebox without selectively usable side extensions tocover the same 48-foot street. I

My mobile heater may also be used for melting snow and ice fromthestreets; or for drying them; the latter use having been employed onracetracks; and .it is of course obvious that the adjustable-widthfeature makes it possible to accomplish -al1'these tasks moreeconomically thanv would otherwise be the case. p

Pursuant tothe uses justsetforth, an important-object of the inventionis to provide the hood with hinged side extensions that may be rotatedout of the way when their use is not required.

A further object is to provide linkage means operable by the lateralmovement of the hood itself for rotating the hinged extensions.

An additional object is to provide the heater or firebox with removablesides for use when the hinged extensions are not required.

Still another object of the present invention is to provide an improvedfirebox construction that will produce a better spread of the fire.

Yet another object is to reduce the smoke produced by providing anafter-burner effect in the the rear part of the hood.

Still other objects will appear as the specification proceeds.

In the drawings:

FIG. 1 is a side elevation of a mobile surface heater embodying myinvention.

FIG. 2 illustrates a conventional means that may be used for connectingthe chassis of my heater structure to the transporting truck.

FIG. 3 is a cross-section taken on line 33 of FIG. 1.

FIG. 4 is a longitudinal section through my improved firebox or heatinghood.

FIG. Sis a section taken on line 5-5 of FIG. 1.

FIG. 6 is a section taken generally on line 6-6 of FIG. 1. I

FIG. 7 is an enlargement of the parts shown within the circle at theleft in FIG. 5.

FIG. 8 is a view taken on line 88 of FIG. 7.

FIG. 9 is a section taken on line 9-9 of FIG. 1.

The supporting chassisof my surface heater is a generally rectangularframe 19 of substantially the construction shown in my earlier patent.This rectangular frame may be supported at the rear by two downwardlyextending extensions 10b, FIGS. 1 and 3, which are attached to memberbetween the wheels 95. At the front end, individual extensions 19a ofthe side members of the chassis frame lti may appropriately extenddownwardly and inwardly at an angle as shown in FIG. 2, where they areconnected to a disc or fifth wheel 97 that is pivotally supported on amating structure or fifth wheel 93 carried by a truck or tractor 55.Attached to and depending from the side members of the frame 10 are twoparallel I-beams 11 and 12. A shiftable rigging 13 is movably supportedon the lower flanges of these I-beams 11 and 12 by means ofroller-bearing equipped hanger carriers 14, 15, 16 and 17. The rigging13 comprises two parallel longitudinally disposed I-beams 2t and 21 andtwo spaced and transversely disposed parallel I-beams 22 and 23 weldedor otherwise rigidly connected to members 29 and 21 to form arectangular frame.

The hanger carriers 14 and 16 are assembled to I-beam 18 which extendsacross the rigging 13 and is rigidly connected to the longitudinallyextending side members 20 and 21, and hanger carriers 15 and 17 are inlike manner assembled to I-beam cross-member 19 which is also rigidlyattached to the'side members. Each of the carrier assemblies comprisestwo opposed side plates 24 and 25, which are generally triangular inshape. A pair of flanged carrier Wheels are rotatably'mounted on each ofthe plates 24. and a pair of identical flanged supporting wheels aresimilarly rotatably mounted on each of the plates 25. Hanger carriers 14and 16 are rigidly connected to I-beam cross member 18 by means of bolts27 and 28, respectively, FIG. 9, which pass through the I- beam. Thehanger carriers 15 and 17 are similarly attached to cross-member 19 bymeans of bolts 29 and 30, FIG. 5.

The hanger carriers just described make it possible for the frame orcarriage 13, comprising the two longitudinal members 26 and 21 and thefour cross-members 18 and 19, 22 and 23, to be shifted laterally. T oprevent the hanging carriage from slipping entirely off of the lowerflanges of the cross-beams 11 and 12, which act as supporting tracks, Iprovide two limiting struts, each of which comprises a diagonal arm 31.One arm 31 joins with an abutting section 2, and arm 31 at the right ina similar manner joins an abutting section 33. It will be observed inFIG. 6 that the shiftable carriage comprising longitudinal members 20and 21 and cross members 22 and 23 cannot be moved farther to the leftbecause the longitudinal beam 20 is abutting against section 33. Themovement of the carriage to the right is similarly limited by theengagement of I-bearn 21 and the abutting section 32.

Two rotatable shafts 34 and 35 extend all the way across, and overhangthe cross carriage 13 as may be seen in FIGS. 1 and '6, the latterfigure showing shaft 35 only. Each of these shafts is journaledin a pairof bearings 36, FIG. 6, appropriately attached to the longitudinal beamsby a pair of U-bolts 37. v v

The two shafts 34 and 35 are so connected by. link 38 and lever arms 33and 40 that they turn as a unit. The lever arm 39 is rigidly attached toshaft 34 intermediate its ends, and lever arm 40 is likewise rigidlyconnected to shaft 35. The outer ends of these two arms 39 and 40 arepivotally connected to opposite ends of the interconnecting link 38.Lever arms 41 and 42 are solidly connected to opposite ends of shaft 35,FIG. 6, and a similar set of lever arms 43; and 44 are rigidly attachedto opposite ends of shaft 34. The outer end of arm/i1 is pivotallyconnected to a linkage 45, and arm 42 issim ilarly pivoted to a linkage46, FIG. 5. Lever 43 is con 'nected to a linkage 47, FIGS. -1 and 6, andthe companion lever arm 44 is connected inlikemanner to another suchlinkage 48. The lower ends of linkages 45, 46, 47 and 48 are pivotallyconnected to the top of the heating hood or firebox 49, FIGS. 1 and 4,by means of brackets 50, FIG. 4. It will be obvious thatcounterclockwise rotation of shafts 34 and 35 will cause the firebox 49to be raised and that the clockwise rotation of these shafts will lowerthe firebox. This movement is controlled hydraulically by the cylinder51 and the piston throw-leverSZ operat-' ing therein. 7 This throw-leveris appropriately pivoted at its outer end to arm 40 by means ofarr-interconnecting bracket 53, and the cylinder 51 is itself pivotallymounted to the frame 13 by means of bracket 54. The hydraulic cylinder51 is operated from the cab 55 by controls shown and described in myPatent No. 2,558,160.

The heating hood or firebox '49 is longitudinally braced and stabilizedwith respect to the frame 13 by means of a pair of angularly disposedrods 104 and 105, FIGS. and 6, rod 104 being shown also in FIG.. 1. Theupper end of rod 104 is pivotally anchored to 'I-beam 2% of thetransversally shiftable carriage'13 by means of bracket 106, FIG. 6, andthe corresponding end of the bracing rod 195 is similarly pivotallyanchored to I-beam 21 of the shiftable carriage by bracket 107. i v

The cross travel of the laterally movablecarriage is accomplished bymeans of the hydraulic jack 56 and its plunger 57, PEG. 6, the outeren'd'of which is appropriately interconnected to the cross carriage. Asis the case with jack 51-, the jack 56 iscontrolled from the cab byappropriate hydraulic connections, such'as those disclosed in myearlier-patent.

In order to extend the broadside coverageof my heater or hood beyond thelimits permitted by my earlier structure, I attach two hinged extensionstructures 58 and 59 to opposite sides of the heater 49, as showninFIGS. 5 and 9. These side extensions are L-shaped in cross-see tionandare pivoted by means of a plurality 'of brackets attached to the coverand theside panel. One or more brackets 63 are attached to the top coverof each hinged extension intermediate its outer wall or side panel 64and the pivot point 65. A link 66 is detachably connected at one endthereof to one of the brackets 63 on the left side extension 58 and atthe other to a bracket 67, which is rigidly attached to one end of oneof the cross beams 12 that depend from the chassis frame 10 as shown inFIG. 5.

Such brackets 63 as may be attached to the right pivotal extension 59are each detachably connected to a bar such as link 68 which isremovably pivoted to a bracket 69 on the right end of the cross beam 12.These links are disconnected at at least one end whenever theintermediate carriage and firebox are to be moved laterally and wheneverthe entire mobile unit is to be moved from one site to another.

When neither of the hinged side extensions 58 or 59 is being employedduring the time that the firebox is in operation, a side plate 70, FIGS.5, 7 and 8, is hung over the otherwise open side of the firebox. Thisplate may appropriately be made of A thick heat-resistant stainlesssteel. The two side plates may be removably hung to the top edge of theopen side of the firebox by means of chains 71 or other appropriateinstrumentalities;

The structure hereinbefore described makes it possible to raise andlower the extensions solely by the power available hydraulically throughthe two jacks 51 and 56. If the distance from the hinge point 65 ofeither side extension, FIG. 5, to the corner 101 of the top surface andassociated side panel 64 is 18 inches and if the bar 66 is 2 feet 3inches long, then either of the side extensions can be raised or loweredby a two-foot lateral movement of the firebox 49. At the beginning ofthe raising movement, the rigid links 66 and 68 may be disposed insomewhat the position of link 68 shown on the right side of FIG. 5. Atthe end of the movement; the various parts will appear in the positionsin which extension 58 and link 66 are shown on the left side of thisfigure. During the actual raising and lowering'of the sides, however,links 66 and 63 are seldom, if ever, both connected at the same time.One reason for this will be apparent if we consider what would happen ifthe firebox should be moved to the right from the position shown in FIG.5 while both links are connected and while the firebox is at the levelshown in th'efigure. Any movement of the firebox to the right wouldobviously result in buckling the link 68. This can of course be avoidedby lowering the firebox sufiiciently to cause the link 68 to pull upwardon the bracket 63 on the top of the extension structure 59 and rotatethe structure far enough counterclockwise about its axis of rotation topermit the lower end of link 68 to swing downward in an are as thefirebox is moved to the right. This downward movement of the firebox isnot possible, however, so long as rod 66 above the left .side' of thefirebox remains connected, as no lowering of the pivot 63 at the bottomend of link 66 can take place for the reason that this would cause link66 to rotate counterclockwise and the extension 'str'uctiire as to turnclockwise, a movement that is not possible without bending 'or breakingsomething since the striictur'e 64 is already in its extreme clockwiseposition But let us suppose link 65 is disconnected. The extension 59then may-be rotated counterclockwise to 'a 61 attached thereto, eachhaving a pivotal connection with another bracket 62 mounted on top ofthe firebox. Each of the side extensions has a top cover, a side panelrid-depending" from one edge of the cover, a front element and a backelement, each of these elements being position in which it will .restagainst the right bracket 72 by first lowering the firebox enough toprovide room for a downward swing of the lower end of link- 68 as thefire-- box is moved to the right. This will then of course cause theextension structure-5? to turn clockwiseslightly durcourse first beremoved. If we are to lower the extension side structure 58 to itsoperative position from its rest position shown in FIG. 5, link 68 onthe other side of the equipment must first be disconnected at one orboth ends. The firebox may then be moved to the right. As it does so,the link 66 will press on pivot 63. Inasmuch as the line of forceexerted by link 65 is considerably above the center of rotation 65 ofthe side extension 58, there is a moment arm to receive the force, andthe structure 58 consequently turns counterclockwise in response to themovement of the firebox to the right until the side structure 58 is inan operative position in which its top is aligned with the top of thefirebox.

It will be observed in FIG. 5 that the raised extension 58 is sodisposed that the portion thereof which extends furthest to the left isalmost directly over the plate 70. This indicates that when bothextensions are raised, the distance across the entire hood, plus theparked hinged extensions, will be no greater than the distance acrossthe hood itself from one side plate to the other.

When the extensions are raised to the position shown at the left in'FlG.5, they will rest on the brackets 72, which are attached to the top ofthe heater.

Other means than the hydraulic power available on the chassis may ofcourse be employed for raising or lowering the extension sides, as, forexample, a hand winch mounted on the chassis or firebox, or a skiploader that may be used to lift the extension side by means of its loweredge.

My improved hood, or firebox, provides more even distribution of theheat than is possible with previous structures, and it also reducessmoke by an after-burner ef fect, hereinafter described. In thelongitudinal section of my firebox shown in FIG. 4, a bulge 73 is shownin the insulated top section. This forces the flames down against thesurface of the road and toward the back end 74 of the firebox. Fuelburning nozzles are of course arranged along the front end as shown inFIG. 9 where a plurality of nozzles F5 may be seen. These areindividually inserted in, or aligned with, individually associatedopenings like opening 76 shown in MG. 4. These nozzles are supplied withfuel through individual tubes 192 connected to the fuel manifold 77. Thenozzles are supplied with air through individual pipes 73 connected toan air manifold 79 that communicates through a duct 89, FIGS. 9 and l,with a blower 81 in the truck 55'.

In my improved heater, I provide an auxiliary air manifold 82 in thebulge. This is supplied with air from the main air manifold 79 by meansof short pipe 114, elbow 115, pipe 1%, elbow 116 and short pipe 117. Aplurality of burners, such as burner 83, each receiving its air from theauxiliarymanifold 82, may be aligned along the bulge '73 where eachcommunicates with the inside of the fire hood by means of duplicates ofopening ill. Fuel is furnished to these additional burners by tubes suchas tube 12% from the auxiliary fuel manifold 119 which receives itssupply through tube 118 from the main fuel manifold 77. These extraburners assist-the combustion of any unburned gases that may havereached the vicinity of the nozzles in the bulge, thus materiallyreducing the waste caused by unburned fuel and minimizing the fumes andsmoke that would otherwise reach the surrounding atmosphere.

ltwill be noted that the top portion of the hood near the end '74, heredesignated by the numeral 36, slants downward, as does also the thickinsulation 37 attached thereto. This directs the, fire and heat downwardtoward the roadbed under the open side of the hood.

Individual nozzles are provided for the hinged side extensions. One suchnozzle, designated by'the numeraldd, is shown in association with sideextension 59 in FIG. 9, and an aperture 92 is shown in the end elementof the opposite side extension 53 for another nozzle like the one shownon the right side. Nozzle 33 is supplied with air through pipe 89, whichis connected by elbow 914to a short pipe Q3 communicating with the airmanifold 79.

Before raising the extension 59 nozzle 88 with its supply pipe 89 mustbe rotated out of the way, the elbow 94 rotating on the short pipe 93 atthe juncture of the elbow 94 and pipe 93. Tube 91, which supplies fuelto the nozzle 88, is a flexible tube, and therefore flexes when nozzle88 and tube 5% are rotated to an inoperative position. The fuel is thenturned ofi by means of valve 133.

The hinged side extensions hereinbefore described may of course be usedwith a mobile chassis having no laterally movable subcarriage, and theimproved firebox has increased utility even for such purposes asroasting ore.

Various modifications may of course be made from.

the illustrative embodiments herein described and shown in the drawings,and substitutions of other parts performing the same functions may bemade for the various elements set forth in the appended claims.Moreover, transpositions and rearrangements may be made withoutdeparting from the broad spirit of my invention.

The inventor claims:

1. In a mobile surface heater, a combination including: a generallyhorizontal suspension frame; means for attaching one end of said frameto a towing vehicle; means for supporting other end of said frame on anaxle carried between two wheels; a rig movably depending from said framefor, lateral movement; a firebox disposed beneath said rig and at leastindirectly supported thereby, said firebox having an open bottom andcomprising a top member, a front wall, a back wall and at least oneelongated angularly movable side extension structure hav- ,ing a topcover, a front element, a back element and a side panel depending fromone side edge of the top cover,

' said structure being so hinged to said top member that the edge of thetop cover opposite from said one side edge lies adjacent one edge ofsaid top member in one angular position of said structure; means carriedby said rig for raising and lowering said firebox; a rigid bar removablypivoted at one end to said frame and at its other end to said extensionstructure intermediate its axis of rotation and its side panel, said baracting to rotate said extension structure selectively to and from itsoperating position in response to lateral movement of said rig; and aremovable side for the firebox to close the otherwise open side of thefirebox when the extension side structure is not being used.

2. In a mobile surface heater, a combination including: a generallyhorizontal suspension frame; means for attaching one end of said frameto a towing vehicle;

means for supporting the other end of said frame on an,

axle carried between two wheels; a rig movably depending from said framefor lateral movement; a firebox dis.-

posed beneath said rig and at least indirectly supported thereby, saidfirebox having an open bottom and comprisa having a top cover, a frontelement, a back element and a side panel depending from-one side edge ofthe top cover, said structure being so hinged to said top member thatthe edge of the top cover opposite from said one edge lies adjacent oneedge of said top member in one angular position of said structure; meanscarried by said rig for raising and lowering said firebox; a rigid barremovably pivoted at one end to said frame and at its other end to saidextension structure intermediate its axis of rotation and its sidepanel, said bar acting to rotate said extension structureselectively toand from its operating position in response to lateral movement of saidrig; a removable side for the firebox "to close the otherwise open sideof the firebox when the extension side structure is not being used; andmeans for limiting the angular movement of said extension structure whenit is rotated to an inoperative position over said firebox.

3. In a mobile surface heater, a combination including: a generallyhorizontal suspension frame; means for attaching one end of said frameto a towing vehicle; means for supporting the other end of said frame'onan axle carried between two wheels; a rig movably depending from saidframe for lateral movement; a firebox disposed beneath said rig and atleast indirectly supported thereby, said firebox having an open bottomand comprising a top member, a front wall, a back wall and at least oneelongated angularly movable side extension structure having a top cover,a front element, a back element and a side panel depending from one sideedge of the top cover, said structure being so hinged to said top memberthat the edge of the top cover opposite from said one side edge liesadjacent one edge of said top member in one angular position of saidstructure; means carried by said rig for raising and lowering saidfirebox; power operated means carried by said frame and attached to saidrig for moving the rig; a rigid bar removably pivoted at one end to saidframe and at its other end to said extension structure intermediate itsaxis of rotation and its side panel, said bar acting to rotate saidextension structure selectively to and from its operating position inresponse to lateral movement of said rig; and a removable side for thefirebox to close the otherwise open side of the firebox when theextension side structure is not being used.

4. In a mobile surface heater, a combination including: a generallyhorizontal suspension frame; means for attaching one end of said frameto a towing vehicle; means for supporting the other end of said frame onan axle carried between two Wheels; a rig movably depending from saidframe for lateral movement; a firebox disposed beneath said rigand atleast indirectly supported thereby,

said firebox having an open bottom and comprising a top member, a frontwall, a back wall and at least one elongated angularly movable sideextension structure having a top cover, a front element, a back elementand a side panel depending from one side edge of the top cover, at leastone of said walls having a plurality of openings therein and at leastone of said elements having an aperture therein, said structure being sohinged to said top member that the edge of the top cover opposite fromsaid one side edge lies adjacent one edge of said top member in oneangular position of said structure; means carried by said rig forraising and lowering said firebox; a rigid bar reinovably pivoted at oneendto said frame and. at its other end to said extension structureintermediate its tion; means carried by said rig for raising andlowering said firebox; and a removable plate for closing the otherwiseopen side of the firebox when said extension side structure is rotatedto an inoperative position.

axis of rotation and its side panel, said bar acting to rotate saidextension structure selectively to and from its operating position inresponse to lateral movement of said rig; a removable side for thefirebox, to close the otherwise open side of the firebox when theextension side structure is not being used; a plurality" ofair-and-fuelsupplied nozzles, each aligned with one of said openings forproducing flames inside said. firebox; an air-supply pipe; and anadditional air-and-fuel-supplied nozzle so supported thereby, saidfirebox having an open bottom and comprising a top member, a front wall,a back wall and at least one. elongated angularly movable side extensionstructure having a top cover, a front element, a back element and a sidepanel depending from one side edge of thetop cover, said structure beingso hinged to the top member of the firebox that the structures top coverbecomeseifectively an extension of said top member when said structureis in an operative angular posi- 6. In a mobile surface heater, acombination includ ing: a general horizontal suspension frame; means forattaching one end of said frame to a towing vehicle; means for movablysupporting the other end of said frame; a rig movably depending fromsaid frame for lateral movement, a firebox disposed beneath said rig andat least indirectly supported thereby, said firebox having an openbottom and comprising a top member, a front wall, a back wall and'a pairof elongated angularly movable side extension structures each having atop cover, a front element, a back element and a side panel dependingfrom one side edge of the top cover, each of said structures being sohinged to the top member of said firebox that the structures top coverbecomes effectively a continuation of said top member when saidstructure is in an operative angular position; means carried by said rigfor raising and lowering said firebox; and a pair of plates eachremovably attachable to the firebox for closing an otherwise open sidethereof when the extension structure hinged above said open side isrotated to an inoperative position above the firebox.

7. In a mobile surface heater, a combination including: a generallyhorizontal suspension frame; means for attaching one end of said frameto a towing vehicle; means for movably supporting the other end of saidframe; a firebox at least indirectly supported by said frame, saidfirebox having an open bottom and comprising a top member, a front wall,a back wall and at least one elongated angularly movable side extensionstructure having a top cover, a front element, a back element and a sidepanel depending from one side edge of the top cover, said struc turebeing so hinged to the top member of the firebox that the structures topcover becomes effectively an extension of said top member when saidstructure is in an operative angular position; means at least indirectlysupported by said frame for raising and lowering said firebox; and aremovable plate for closing the otherwise open side of the firebox whensaid extension structure is rotated to an inoperative position.

8. In a mobile surface heater, a combination including: a generallyhorizontal suspension frame; means for attaching one end of said frameto a towing vehicle; mobile means for supporting the other end of saidframe; a firebox at least indirectly supported by said frame, saidfirebox having an open bottom and comprising a top member, a front wall,a back wall and a pair of elongated angularly movable side extensionstructures each having a top cover, a front element, a back element anda side panel depending from one side edge of the top cover, each of saidstructures being so hinged to the top member of the firebox that thestructurestop cover becomes effectively a continuation of said topmember when said structure is in an operative angular position; means atleast indirectly supported by same frame for raising and lowering saidfirebox; and a pair of plates each removably attachable to the fireboxfor closing an otherwise open side thereof when the extension structurehinged above said open side is rotated to an inoperative position abovethe firebox.

9(The combination of claim 5 with the addition of means for limiting theangular movement of said extension structure when it is rotated to aninoperative position over said firebox.

. 10. The combination of claim 6 with the addition of means for limitingthe angular movement of said extension structures when they arerotatedto their inoperative positions over said firebox.

l1. Thecombination of claim 7 with the addition of means for limitingthe angular movement of said extension structure when it is rotated toan inoperative position'o'ver said firebox. v

8 12. The combination of claim 8 with the addition of means for limitingthe angular movement of said extension struotures when they are rotatedto their inoperative positions over said firebox.

References Cited by the Examiner UNITED STATES PATENTS 582,420 5/97Hancock 126-2712 18 McKeen et a1. 126-2712 Ward 126-271.2 Williams et a1126271.2 X

Sowell 126271.2

FOREIGN PATENTS 11/48 Australia.

1/47 Great Britain.

875,817 1/08 Howard 126271.2 10 JAMES W. WESTHAVER, Primary Examiner.

7. IN A MOBILE SURFACE HEATER, A COMBINATION INCLUDING: A GENERALLYHORIZONTAL SUSPENSION FRAME; MEANS FOR ATTACHING ONE END OF SAID FRAMETO A TOWING VEHICLE; MEANS FOR MOVABLY SUPPORTING THE OTHER END OF SAIDFRAME; A FIREBOX AT LEAST INDIRECTLY SUPPORTED BY SAID FRAME, SAIDFIREBOX HAVING AN OPEN BOTTOM AND COMPRISING A TOP MEMBER, A FRONT WALL,A BACK WALL AND AT LEAST ONE ELONGATED ANGULARLY MOVABLE SIDE EXTENSIONSTRUCTURE HAVING A TOP COVER, A FRONT ELEMENT, A BACK ELEMENT AND A SIDEPANEL DEPENDING FROM ONE SIDE EDGE OF THE TOP COVER, SAID STRUCTUREBEING SO HINGED TO THE TOP MEMBER OF THE FIREBOX THAT THE STRUCTURE''STOP COVER BECOMES EFFECTIVELY AN EXTENSION OF SAID TOP MEMBER WHEN SAIDSTRUCTURE IS IN AN OPERATIVE ANGULAR POSITION; MEANS AT LEAST INDIRECTLYSUPPORTED BY SAID FRAME FOR RAISING AND LOWERING SAID FIREBOX; AND AREMOVABLE PLATE FOR CLOSING THE OTHERWISE OPEN SIDE OF THE FIREBOX WHENSAID EXTENSION STRUCTURE IS ROTATED TO AN INOPERATIVE POSITION.